after

afterの画像を可変させる

background-image: url(xxx.png);
background-size: 80% auto;
background-repeat: no-repeat;
background-position: center top;
padding-top: 55%;

●content: urlをリセット
content:””;
完全に打ち消す
content:none;

div:after {
content: ”;
width: 100%;
height: 50px;
display: block;
background: url(../img/bg.jpg) no-repeat 50% 100%;
}